Hypertension is a major cardiovascular disorder affecting 18% of the adult population in the United States. The goal of antihypertensive therapy is to minimize end-organ damage that can lead to kidney failure, stroke, and coronary heart disease. In addition, hypertension itself has been shown to be associated with impaired psychological functioning that may be reversed with blood pressure normalization. The present study is designed to test the hypothesis that chronic aerobic exercise will reduce blood pressure and improve quality of life in hypertensive men and women. One hundred twenty men and women with mild hypertension and 40 normotensive controls will serve as subjects for this study. First, the cognitive performance of hypertensives and normotensives will be compared. Second, hypertensive subjects will be randomly assigned to an aerobic exercise program, to a toning and flexibility group, or to a waiting list control group. Upon entry and after four months, subjects will undergo comprehensive evaluations including blood chemistries, symptom-limited treadmill testing, ambulatory blood pressure monitoring, and cognitive and psychometric testing. Subjects also will undergo a behavioral challenge to assess cardiovascular and neuroendocrine responsivity. We hypothesize that a program of regular exercise will attenuate cardiovascular and neuroendocrine responsivity, reduce blood pressure as measured in the laboratory and in the natural environment, and improve cognitive functioning. We will also examine the role of individual differences in responses to exercise training, including considerations of ethnicity and sympathetic nervous system tone. This project has important scientific significance by proposing to systematically evaluate the effects of aerobic exercise on blood pressure in patients with mild hypertension. The study also has important practical significance by evaluating the efficacy of non-pharmacologic management of hypertension. If successful, aerobic exercise could be implemented as a cost-effective strategy for reducing the physical, psychological, and economic costs associated with hypertension.